or
Subelement O
Section 90
What is the normal range of pulse repetition rates?
• 2,000 to 4,000 pps.
• 1,000 to 3,000 pps.
• 500 to 1,000 pps.
500 to 2,000 pps.

What is the normal range of pulse repetition rates?

500 to 2,000 pps.

The pulse repetition rate is how many pulses are created in a unit of time. The radar will turn on and off in its carrier frequency. The pulse is the number of on/off switching that the radar does per second.

Other wave bands are described as cycles per second, which is kind of like on/off switching per second. Same idea for sonar systems.

The pulse repetition frequency (PRF) has an inverse relationship with time. That is, 1 unit of time (second) divided by the PRF

$\frac{1 }{\text{PRF}} = \text{ Time, (second)}$

Also see Radar Tutorial Eu for the article on Pulse Repetition Frequency (PRF)

Highly useful Unit Converter on Translator Scale site, for Radar Maximum Unambiguous Range and Pulse Repetition Frequency Calculator

Reference: Radar specifications and use are listed in the Code of Federal Regulations, Title 47 Chapter I Subchapter D
Part 80 - STATIONS IN THE MARITIME SERVICES

Since applicable regulations are in a number of places, please use CTRL-F and search on the word "radar" to look up applicable regulations.

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The RADAR range in nautical miles to an object can be found by measuring the elapsed time during a RADAR pulse and dividing this quantity by:
• 0.87 seconds.
• 1.15 µs.
12.346 µs.
• 1.073 µs.

The RADAR range in nautical miles to an object can be found by measuring the elapsed time during a RADAR pulse and dividing this quantity by:

12.346 µs.

For the range in nautical miles, determine the time it took the signal to bounce and come back, and then divide the amount by 12.36. For range in kilometers, divide by 6.66.

Remember that the speed of light is 300 million meters per second, while in nautical miles it is approximately 161,784 nautical miles per second.

The radar pulse travels about 6.2 µs (microseconds) a distance of 1 nautical miles, and the same to come back. So, round trip is twice 6.2 µs (6.173 µs) or 12.36 µs.

For well-illustrated explanation, please see Radar tutorial EU article on Range or distance measurement

For mathematical formulas, please see Tutorialspoint articles on Radar Systems - Overview and Radar Systems - Range Equation

Reference: Radar specifications and use are listed in the Code of Federal Regulations, Title 47 Chapter I Subchapter D
Part 80 - STATIONS IN THE MARITIME SERVICES

Since applicable regulations are in a number of places, please use CTRL-F and search on the word "radar" to look up applicable regulations.

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What is the normal range of pulse widths?
• .05 μs to 0.1 μs.
.05 μs to 1.0 μs.
• 1.0 μs to 3.5 μs.
• 2.5 μs to 5.0 μs.

What is the normal range of pulse widths?

.05 μs to 1.0 μs.

One second equals 1,000,000 µs microseconds, or 10-6.

The RADAR has to adjust the number of pulses per second, as it determines the pulse width. The pulse has to be long enough so that the receiver can pick up the echo. The workable range of the number of pulses results in the .05 μs to 1.0 μs width.

Please see Wikipedia's article on Pulse Width

Also see Alternative Wars site for the article Computing Radar Characteristics.

For well-illustrated info, please see Radar Tutorial EU site for the article on Minimal Measuring Range and Pulse Radar.

Reference: Radar specifications and use are listed in the Code of Federal Regulations, Title 47 Chapter I Subchapter D
Part 80 - STATIONS IN THE MARITIME SERVICES

Since applicable regulations are in a number of places, please use CTRL-F and search on the word "radar" to look up applicable regulations.

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Shipboard RADAR is most commonly operated in what band?
• VHF.
• UHF.
SHF.
• EHF.

Shipboard RADAR is most commonly operated in what band?

SHF

The Super High Frequency band is from 3 GHz to 30 GHz, which means that the waves are from 10 centimeters to 1 centimeter (10 cm to 1 cm). The SHF was defined by the International Telecommunications Union, ITU.

The 3 GHz to 30 GHz can be written as 3,000 MHz to 30,000 MHz.

Giga is 1,000,000,000 or billion, and Mega is 1,000,000. So the difference between Mega and Giga is 1,000.

The SHF waves can transmit to approximately 60 miles. Due to its properties such as clearly identifying metal objects because of its reflection and the narrow wave simulating a beam, it is highly used in Radar technology.

For an excellent and well illustrated overview of the use of frequency ranges, please see Radar Tutorial EU, for the article Waves and Frequency Ranges

Reference: Radar specifications and use are listed in the Code of Federal Regulations, Title 47 Chapter I Subchapter D
Part 80 - STATIONS IN THE MARITIME SERVICES

Since applicable regulations are in a number of places, please use CTRL-F and search on the word "radar" to look up applicable regulations.

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The pulse repetition rate (prr) of a RADAR refers to the:
• Reciprocal of the duty cycle.
• Pulse rate of the local oscillator.
• Pulse rate of the klystron.
Pulse rate of the magnetron.

The pulse repetition rate (prr) of a RADAR refers to the:

Pulse rate of the magnetron.

Also, see Radar Tutorial EU site for the very well illustrated article Magnetron

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If the elapsed time for a RADAR echo is 62 microseconds, what is the distance in nautical miles to the object?
5 nautical miles.
• 87 nautical miles.
• 37 nautical miles.
• 11.5 nautical miles.

If the elapsed time for a RADAR echo is 62 microseconds, what is the distance in nautical miles to the object?

5 nautical miles.

From wp2ahg:

Light travels 186,000 mps, or 161,630 nmps.

If the radar signal was returned in 62 μs microseconds, then the distance to the target was reached in half that time, or 31 μs microseconds.

So, the distance to the target is
161,630 nmps x 0.000031 secs = 5 nautical miles

OR: since radar signal travels 1 nautical mile in 6.2 μs microseconds

$\frac{62 μs}{{6.2 μs * 2}} = {5 \text{ nautical miles}}$

Reference: Radar specifications and use are listed in the Code of Federal Regulations, Title 47 Chapter I Subchapter D
Part 80 - STATIONS IN THE MARITIME SERVICES

Since applicable regulations are in a number of places, please use CTRL-F and search on the word "radar" to look up applicable regulations.

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